BackgroundPancreatic cancer often presents as locally advanced (LAPC) or borderline resectable (BRPC). Neoadjuvant systemic therapy is recommended as initial treatment. It is currently unclear what chemotherapy should be preferred for patients with BRPC or LAPC.MethodsWe performed a systematic review and multi-institutional meta-analysis of patient-level data regarding the use of initial systemic therapy for BRPC and LAPC. Outcomes were reported separately for tumor entity and by chemotherapy regimen including FOLFIRINOX (FIO) or gemcitabine-based.ResultsA total of 23 studies comprising 2930 patients were analyzed for overall survival (OS) calculated from the beginning of systemic treatment. OS for patients with BRPC was 22.0 months with FIO, 16.9 months with gemcitabine/nab-paclitaxel (Gem/nab), 21.6 months with gemcitabine/cisplatin or oxaliplatin or docetaxel or capecitabine (GemX), and 10 months with gemcitabine monotherapy (Gem-mono) (p < 0.0001). In patients with LAPC, OS also was higher with FIO (17.1 months) compared with Gem/nab (12.5 months), GemX (12.3 months), and Gem-mono (9.4 months; p < 0.0001). This difference was driven by the patients who did not undergo surgery, where FIO was superior to other regimens. The resection rates for patients with BRPC were 0.55 for gemcitabine-based chemotherapy and 0.53 with FIO. In patients with LAPC, resection rates were 0.19 with Gemcitabine and 0.28 with FIO. In resected patients, OS for patients with BRPC was 32.9 months with FIO and not different compared to Gem/nab, (28.6 months, p = 0.285), GemX (38.8 months, p = 0.1), or Gem-mono (23.1 months, p = 0.083). A similar trend was observed in resected patients converted from LAPC.ConclusionsIn patients with BRPC or LAPC, primary treatment with FOLFIRINOX compared with Gemcitabine-based chemotherapy appears to provide a survival benefit for patients that are ultimately unresectable. For patients that undergo surgical resection, outcomes are similar between GEM+ and FOLFIRINOX when delivered in the neoadjuvant setting.

Background: The influence of chemotherapy type and vascular margin status after sequential chemotherapy and stereotactic body radiation therapy (SBRT) for borderline resectable pancreatic cancer (BRPC) is unknown.Methods: A retrospective review was performed on BRPC patients treated with chemotherapy and 5-fraction SBRT from 2009 to 2021. Surgical outcomes and SBRT-related toxicity were reported. Clinical outcomes were estimated by Kaplan-Meier with log rank comparisons.Results: A total of 303 patients received neoadjuvant chemotherapy and SBRT to a median dose of 40 Gy prescribed to the tumor-vessel interface and median dose of 32.4 Gyto 95% of the gross tumor volume. One hundred and sixty-nine patients (56%) were resected and benefited from improved median OS (41.1 vs 15.5 months, P < 0.001). Close/positive vascular margins were not associated with worse OS or FFLRF. Type of neoadjuvant chemotherapy did not influence OS for resected patients, but FOLFIR-INOX was associated with improved median OS in unresected patients (18.2 vs 13.1 months, P = 0.001).Conclusion: For BRPC, the effect of a positive or close vascular margin may be mitigated by neoad-juvant therapy. Shorter duration neoadjuvant chemotherapy as well as the optimal biological effective dose of radiotherapy should be prospectively explored.

Purpose: Preoperative radiation therapy (RT) for pancreatic adenocarcinoma reduces positive surgical margin rates, and when delivered to an ablative dose range it may improve local control and overall survival for patients with unresectable disease. Use of stereotactic body RT to achieve a higher biologically effective dose has been limited by toxicity to adjacent radiosensitive structures, but this can be mitigated by stereotactic magnetic resonance image guided adaptive radiation therapy (SMART).Methods and Materials: We describe our single-institution experience of high biologically effective dose SMART before resection of localized pancreatic adenocarcinoma. Toxicity was evaluated according to Common Terminology Criteria for Adverse Events (V 5.0). Tumor response was evaluated according to the College of American Pathologists tumor regression grading criteria.Results: We analyzed 26 patients with borderline resectable (80.8%), locally advanced (11.5%), and resectable (7.7%) tumors who received ablative dose SMART (A-SMART) followed by surgical resection. Median age at diagnosis was 68 years (range, 34-86). Most patients received chemotherapy (80.8%) before RT. All patients received A-SMART to a median dose of 50 (range, 40-50) Gy in 5 fractions. Toxicity data were collected prospectively and there were no acute grade 2+ toxicities associated with RT. The median time to resection was 50 days (range, 37-115), and the procedure types included Whipple (69%), distal (23%), or total pancreatectomy (8%). The R0 resection rate was 96% and no perioperative deaths occurred within 90 days. Pathologic response was observed in 88% of cases. The time from RT to surgery was associated with tumor regression grade (P = .0003). The median follow-up after RT was 16.5 months (range, 3.9-26.2). The derived median progression-free survival from RT was 13.2 months.Conclusions: The initial surgical and pathologic outcomes after A-SMART are encouraging. Preoperative A-SMART was associated with low toxicity rates and no surgical or RT-associated mortality. The surgical morbidity was comparable to historic rates after upfront resection. These data also suggest that the time from stereotactic body RT to surgical resection is associated with pathologic response.(c) 2022 The Authors. Published by Elsevier Inc. on behalf of American Society for Radiation Oncology. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

410 Background: Outcomes remain poor for those diagnosed with unresectable pancreatic cancer. SBRT and IRE have independently demonstrated high rates of local control and minimal toxicity for patients with locally advanced pancreatic cancer (LAPC). Data is limited regarding safety and efficacy in the sequential use of both therapies. Materials and Methods: A single institution retrospective matched cohort analysis was performed for patients with non-metastatic pancreatic cancer treated with induction chemotherapy and SBRT followed by IRE, compared with patients of the same cohort who did not receive IRE. Patients were paired based on age, tumor stage, GTV D95, CA19-9 prior to SBRT, and chemotherapy type to mitigate selection bias in surgical candidates. Overall survival (OS), progression free survival (PFS), freedom from local failure (FFLF) and freedom from distant failure (FFDF) were the primary outcomes compared via Kaplan-Meier survival analysis with log-rank methods. Results: From July, 2014 to February, 2020 17 patients received SBRT followed by IRE. These patients were matched with 17 patients who received SBRT from January, 2012 to March, 2019. Most patients received neoadjuvant FOLFIRINOX (82.4%) and were AJCC 8 stage III (79.4%). Median age of the overall cohort was 65.5 years and 50% were male. Median dose delivered to 95% of gross tumor volume was 32.61 Gy, and median pre SBRT CA19-9 value was 70.5 U/mL. There were no statistically significant differences in matched characteristics between the two cohorts. Among the SBRT+IRE, the median time between IRE and SBRT was 66 days (range:49-467 days). The median OS, PFS, FFLF, and FFDF for IRE+SBRT vs. SBRT alone from SBRT was 10.8 vs 15.1 months, 9.6 vs. 15.3 months, 15.7 vs. 15.3 months, 15.9 vs. 14.4 months respectively (all P > .10). 11 patients in the entire cohort experienced toxicity as a result of their radiation therapy (35%), with one G3 GIB and one patient experiencing G3 abdominal pain. Among the 17 patients who underwent IRE, nine patients experienced toxicity (53%). Most of these events were G3, with two G4 intestinal bleeds. There was zero mortality in the 90 day period post operatively. Conclusions: In a retrospective cohort,non-selective delivery ofIRE afterSBRT demonstrated no oncological benefit for patients with unresectable pancreatic adenocarcinoma compared to only SBRT. Compared to historical experiences of IRE alone, there was no increase in overall toxicity with the combination of SBRT and IRE. The optimal timing, sequencing, and indications for IRE and SBRT in LAPC remain unknown and are best assessed prospectively. [Table: see text]